The present invention provides a resin composition for medical use, resin pellets, and a part for medical use obtained by molding this resin composition, having excellent radiation resistance in which discoloration significantly is reduced even during sterilization treatment using irradiation with radioactive rays, in particular and gamma-rays. The present invention provides a resin composition for medical use comprising 0.1 to 15 parts by weight of a silane compound as a radiation resistant agent with respect to 100 parts by weight of a thermoplastic resin. The thermoplastic resin is preferably a polyvinyl chloride-based resin, and the silane compound is preferably at least one alkoxysilane compound selected from a monoalkoxysilane compound, a dialkoxysilane compound, a trialkoxysilane compound and a tetraalkoxysilane compound. The resin composition may be a hard composition having a Rockwell hardness as defined in JIS K7202 of 35 or more, or may be a soft composition having a durometer A hardness as defined in JIS K6253 of 97 or less.